how long should one wait for rose seeds to sprout? a few of mine came up right away but a lot of them are refusing to show themselves.
Depends how much patience you have. For canina and the like, it is often necessary to go through a cold, then warm, then cold cycle to get germination, if the seeds have matured on the bush into physiological dormancy. If you have a complex cross, with HT or Fl in the mix, probably 6 months in a refrigerator will get the most of the ones that will germinate.
I usually hold seeds a year at 40 F with nitrate in vermiculite. For some crosses that can give 60-80 % germ. The knock-out types are much slower to germ than fancy HTs.
The problem I have with warm cycles is that mold tends to go rampant with the nitrate that I’ve added, plus dead seeds, so maybe some of the viable ones get killed off. Not sure if that’s a fact, or there are just a lot of dead seeds in some batches. Caninas will sprout after 2-3 cycles (cold-warm-cold-warm etc). Freshly harvested canina before the hips soften, may reach over 80 % germ in under 1 yr, while those held a couple more months on the bush are quite refractory until they’ve had multiple cycles.
van Fleet, doing species crosses, generally held onto flats of seed in soil for up to 5 yr. He didn’t have refrigerators so he used the natural climate cycle around Washington DC.
thank you for the great information, I guess I wont throw away anymore that do not germinate the first spring. I plant mine all natural, no chemicals or sprays for mildew, hoping to get good strong roses that wont need sprays.